// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "content/renderer/media/speech_recognition_audio_sink.h"

#include <stddef.h>
#include <utility>

#include "base/logging.h"
#include "base/memory/shared_memory.h"
#include "base/time/time.h"
#include "content/renderer/media/media_stream_audio_source.h"
#include "media/base/audio_fifo.h"
#include "media/base/audio_parameters.h"

namespace content {

SpeechRecognitionAudioSink::SpeechRecognitionAudioSink(
    const blink::WebMediaStreamTrack& track,
    const media::AudioParameters& params,
    const base::SharedMemoryHandle memory,
    std::unique_ptr<base::SyncSocket> socket,
    const OnStoppedCB& on_stopped_cb)
    : track_(track)
    , shared_memory_(memory, false)
    , socket_(std::move(socket))
    , output_params_(params)
    , track_stopped_(false)
    , buffer_index_(0)
    , on_stopped_cb_(on_stopped_cb)
{
    DCHECK(socket_.get());
    DCHECK(main_render_thread_checker_.CalledOnValidThread());
    DCHECK(params.IsValid());
    DCHECK(IsSupportedTrack(track));
    const size_t kSharedMemorySize = sizeof(media::AudioInputBufferParameters) + media::AudioBus::CalculateMemorySize(params);
    CHECK(shared_memory_.Map(kSharedMemorySize));

    media::AudioInputBuffer* buffer = static_cast<media::AudioInputBuffer*>(shared_memory_.memory());

    // The peer must manage their own counter and reset it to 0.
    DCHECK_EQ(0U, buffer->params.size);
    output_bus_ = media::AudioBus::WrapMemory(params, buffer->audio);

    // Connect this audio sink to the track
    MediaStreamAudioSink::AddToAudioTrack(this, track_);
}

SpeechRecognitionAudioSink::~SpeechRecognitionAudioSink()
{
    DCHECK(main_render_thread_checker_.CalledOnValidThread());
    if (audio_converter_.get())
        audio_converter_->RemoveInput(this);

    // Notify the track before this sink goes away.
    if (!track_stopped_)
        MediaStreamAudioSink::RemoveFromAudioTrack(this, track_);
}

// static
bool SpeechRecognitionAudioSink::IsSupportedTrack(
    const blink::WebMediaStreamTrack& track)
{
    MediaStreamAudioSource* native_source = MediaStreamAudioSource::From(track.source());
    if (!native_source)
        return false;

    const StreamDeviceInfo& device_info = native_source->device_info();
    // Purposely only support tracks from an audio device. Dissallow WebAudio.
    return (device_info.device.type == content::MEDIA_DEVICE_AUDIO_CAPTURE);
}

void SpeechRecognitionAudioSink::OnSetFormat(
    const media::AudioParameters& input_params)
{
    DCHECK(input_params.IsValid());
    DCHECK_LE(
        input_params.frames_per_buffer() * 1000 / input_params.sample_rate(),
        output_params_.frames_per_buffer() * 1000 / output_params_.sample_rate());

    // Detach the thread here because it will be a new capture thread
    // calling OnSetFormat() and OnData() if the source is restarted.
    capture_thread_checker_.DetachFromThread();

    input_params_ = input_params;
    fifo_buffer_size_ = std::ceil(output_params_.frames_per_buffer() * static_cast<double>(input_params_.sample_rate()) / output_params_.sample_rate());
    DCHECK_GE(fifo_buffer_size_, input_params_.frames_per_buffer());

    // Allows for some delays on the peer.
    static const int kNumberOfBuffersInFifo = 2;
    int frames_in_fifo = kNumberOfBuffersInFifo * fifo_buffer_size_;
    fifo_.reset(new media::AudioFifo(input_params.channels(), frames_in_fifo));

    // Create the audio converter with |disable_fifo| as false so that the
    // converter will request input_params.frames_per_buffer() each time.
    // This will not increase the complexity as there is only one client to
    // the converter.
    audio_converter_.reset(
        new media::AudioConverter(input_params, output_params_, false));
    audio_converter_->AddInput(this);
}

void SpeechRecognitionAudioSink::OnReadyStateChanged(
    blink::WebMediaStreamSource::ReadyState state)
{
    DCHECK(main_render_thread_checker_.CalledOnValidThread());
    DCHECK(!track_stopped_);

    if (state == blink::WebMediaStreamSource::ReadyStateEnded) {
        track_stopped_ = true;

        if (!on_stopped_cb_.is_null())
            on_stopped_cb_.Run();
    }
}

void SpeechRecognitionAudioSink::OnData(
    const media::AudioBus& audio_bus,
    base::TimeTicks estimated_capture_time)
{
    DCHECK(capture_thread_checker_.CalledOnValidThread());
    DCHECK_EQ(audio_bus.frames(), input_params_.frames_per_buffer());
    DCHECK_EQ(audio_bus.channels(), input_params_.channels());
    if (fifo_->frames() + audio_bus.frames() > fifo_->max_frames()) {
        // This would indicate a serious issue with the browser process or the
        // SyncSocket and/or SharedMemory. We drop any previous buffers and try to
        // recover by resuming where the peer left of.
        DLOG(ERROR) << "Audio FIFO overflow";
        fifo_->Clear();
        buffer_index_ = GetAudioInputBuffer()->params.size;
    }

    fifo_->Push(&audio_bus);
    // Wait for FIFO to have at least |fifo_buffer_size_| frames ready.
    if (fifo_->frames() < fifo_buffer_size_)
        return;

    // Make sure the previous output buffer was consumed by the peer before we
    // send the next buffer.
    // The peer must write to it (incrementing by 1) once the the buffer was
    // consumed. This is intentional not to block this audio capturing thread.
    if (buffer_index_ != GetAudioInputBuffer()->params.size) {
        DVLOG(1) << "Buffer synchronization lag";
        return;
    }

    audio_converter_->Convert(output_bus_.get());

    // Notify peer to consume buffer |buffer_index_| on |output_bus_|.
    const size_t bytes_sent = socket_->Send(&buffer_index_, sizeof(buffer_index_));
    if (bytes_sent != sizeof(buffer_index_)) {
        // The send ocasionally fails if the user changes their input audio device.
        DVLOG(1) << "Failed sending buffer index to peer";
        // We have discarded this buffer, but could still recover on the next one.
        return;
    }

    // Count the sent buffer. We expect the peer to do the same on their end.
    ++buffer_index_;
}

double SpeechRecognitionAudioSink::ProvideInput(media::AudioBus* audio_bus,
    uint32_t frames_delayed)
{
    DCHECK(capture_thread_checker_.CalledOnValidThread());
    if (fifo_->frames() >= audio_bus->frames())
        fifo_->Consume(audio_bus, 0, audio_bus->frames());
    else
        audio_bus->Zero();

    // Return volume greater than zero to indicate we have more data.
    return 1.0;
}

media::AudioInputBuffer*
SpeechRecognitionAudioSink::GetAudioInputBuffer() const
{
    DCHECK(capture_thread_checker_.CalledOnValidThread());
    DCHECK(shared_memory_.memory());
    return static_cast<media::AudioInputBuffer*>(shared_memory_.memory());
}

} // namespace content
